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DonE DonE is offline
Wo ist die Rennstrecke?
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Join Date: Mar 2004
Location: Brooks, GA
Posts: 1,211
Originally Posted by Rob 930 View Post
JFairman said:

I agree with this for aircraft, but the problem with our cars is that we rarely have the ready ability (or foresight) to check that both banks of plugs are actually firing. I've heard of two instances with twin-plug 911s where an entire bank of plugs was not firing (for some reason), unbeknownst to the driver. The engine can seemingly run okay on one set of plugs, but the timing would be set wrong and it may have serious consequences. Before track days, I always unplug one bank of coils, then the other, to make sure my engine is actually firing both sets of plugs.
This is the first I've ever heard of an entire coil pack/bank not firing, but good idea on the check. My LINK EFI system has an alert for injector and ignition failure, but you never know....

On smaller aircraft engines, like a 540 (cu in), in addition to safety, the twin plug ads to the flame propagation which improves torque. Since the motor red lines at 2700 rpm, you need torque right from idle. In our bigger piston motors (1820 cu in), you need twin plugs just to light the fire without reverting to 45 degrees of advance.

Last edited by DonE; 03-07-2008 at 07:53 PM..
Old 03-07-2008, 07:45 PM
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